Issues with Integrating

So a few months ago I had a friend move in with me for a few weeks and she brought along her young children and her two cats. The roomate moved out and just left her cats with me and I'm having issues getting one of them to want to come out and live in my cats space.

I have 11 of my own so I did the usual routine of isolating the new cats in the bathroom away from mine and slowly introduced them. I let them get used to one another's scents through toys/blankets. Smelling and seeing one another through the door then a baby gate. I did this individually with each one of my cats to the new ones.

Lacy had no issues socializing. I had her at first as a kitten before adopting her out but I kept her brother and sister and now it's like she's been here the whole time and gets along with everyone and is comfortable in the shared space.

Freya is skittish though. I'm afraid it's mostly due to the last owners children physically hurting her and yelling at her because she was not like this when her last owner first got her.

She has no issues with my cats entering her space. She just sniffs at my older ones and they ignore her and she plays with the younger ones and they all can eat together in her room and even use her litter box. The problem is that no matter what I try she does not want to come out of that room. She won't go out on her own, even if I close my others in my bedroom and try to let Freya venture into the living room. If I pick her up and even start to open the door to take her out she bolts. Anytime she's made it into the living room it never lasts more than a minute before she's back at the bathroom door.

It's been months and I don't know what to do. I don't want her to have to live in the bathroom but I have no idea what to do beyond what I've already tried and I hate that she's afraid of the rest of the house. I hope someone may have some insight into something I haven't tried yet.

Perhaps you can use some of the suggestions that other members have used:

1.  'ShadowsRescue', and advisor here, has a genius idea, about using a 'wooden screen door with tension rods' so that a cat could still look out, and feel part of the family.

              http://www.thecatsite.com/t/305774/using-a-camping-tent-to-isolate-a-new-kitty-in-my-household       ...Post #20

      2. 'mickNsnicks2mom' set up a room with plenty of wall furniture, scratching posts, and cat trees. Basically having an area that cats can escape to for high areas, and low areas, as well.

              [thread="297074"]Snick And Jaspers New Cat Wall Furniture​[/thread]      ...Post #1

      3. 'mickNsnicks2mom' also posted a thread, with links to a houzz article, which may offer some other ideas. Sure some of the things mentioned are very expensive, but you can use plain old cardboard        boxes, and regular shelves, and tables for ideas. It just might spark some ideas.

             http://www.thecatsite.com/t/289917/indoor-playland-for-rescued-cats-a-houzz-article

I think it's good that Freya likes to play with the younger cats.

You can use 'Play' to your advantage, and get her more comfortable since she likes playing.

Somehow, it sounds like Freya needs to have her confidence boosted, and using interactive play, or using treats or food, to get her to come out of her room, might help.

Softly reading out loud to Freya, getting used to your voice, getting down to her level and talking to her, might all help with building up her confidence.